1. Field of the Invention
The present invention relates to a crossconnecting device used for a synchronous digital hierarchy (SDH) transmission apparatus or a synchronous optical network (SONET) transmission apparatus and an operation system for monitoring and controlling the transmission apparatus.
2. Description of the Related Art
Paths (a bundle of channels) different in a destination are multiplexed on a transmission line, these paths are converged, are isolated or are interchanged by a crossconnecting device and are transmitted on a suitable line. The crossconnecting device can enhance the utilization efficiency of a transmission line network and can produce an economical and reliable path. To monitor and control the crossconnecting device, an operation system constituted of an information processing unit such as a workstation and a personal computer is connected.
Heretofore, in a network of transmission apparatus using an SDH/SONET system, the size of a path (physically equivalent to transmission speed) is specified beforehand when a path is set and afterward, is kept fixed. Only when a path is set, the size can be changed and in case the size is to be changed, the path is once required to be released.
However, in a conventional type path setting system, the description of the size is not included as in “6. Higher order SDH path layer” of ITU G.783 Standard which is a standard of a multiplexer and Bellcore GR-253-Core Standard (refer to FIGS. 2-1, 2-2).
To correspond to multimedia such as a high quality television in future, the realization of a broadband integrated service digital network (ISDN) is essentially required, to realize broadband ISDN, an asynchronous transfer mode (ATM) is also important technology and they are expected as the information communication infrastructure of the twenty-first century.
Therefore, in future, it is estimated that computerization will be further developed together with the rapid change of economics, public society, life and culture in addition to the progress of technology. A future transmission network is required to be simple and to have high operability so that the network can flexibly correspond to various service. Further, to reduce the cost, the operation, the maintenance and the control of the network are also required to be simplified.
Under such a situation, in a network of transmission apparatus using the conventional type SDH/SONET system, the size of a path is fixedly managed, it is not allowed as a system that pathsize is changed after a path is set and in case the size is to be changed, new pathsize is required to be set again. Under such a situation, it is difficult to enhance the service capacity and simplify the maintenance and control of the network.